Antimicrobial cellulose sponge and method of making

Abstract

Biguanide bonded within a cellulose sponge inhibits or prevents the growth of microorganisms such as bacteria, mold, and fungus within the cellulose sponge over the useful life of the cellulose sponge.

1. A method of maintaining the ability of a cleaning structure to be antimicrobial, the method consisting of:
 providing an anionically functionalized cellulose sponge, wherein the anionic functional groups are formed during the manufacture of the cellulose sponge; 
 absorbing into the cellulose sponge an input solution consisting of water and biguanide having cationic functional groups; 
 bonding the cationic functional groups of the biguanide to the anionic functional groups of the cellulose sponge; and 
 packaging the cellulose sponge with biguanide bonded thereto in a sealed package; 
 wherein the packaged cellulose sponge optionally includes a material selected from the group consisting of a dye, a perfume, a fragrance, a surfactant, and reinforcing fibers; 
 wherein the packaged cellulose sponge does not include humectant; and 
 wherein the cellulose sponge maintains at least 0.02 weight percent bonded biguanide, based on a dry weight of the cellulose sponge, following 100 cycles of rinsing and wringing with water to provide at least a three log reduction in microorganisms in the cellulose sponge. 
 
     
     
       2. The method of  claim 1 , wherein the reduction in microorganism in the cellulose sponge occurs within 5 minutes. 
     
     
       3. The method of  claim 1 , wherein the cellulose sponge maintains at least 0.5 weight percent bonded biguanide, based on the dry weight of the cellulose sponge, following 100 cycles of rinsing and wringing with water, to provide a 100% reduction of microorganisms in the cellulose sponge. 
     
     
       4. The method of  claim 1 , wherein the packaged cellulose sponge contains at least 0.4 weight percent bonded biguanide, based on the dry weight of the cellulose sponge. 
     
     
       5. The method of  claim 4 , wherein the packaged cellulose sponge contains at least 1.25 weight percent bonded biguanide, based on the dry weight of the cellulose sponge. 
     
     
       6. The method of  claim 4 , wherein the cellulose sponge maintains at least 0.5 weight percent bonded biguanide, based on the dry weight of the cellulose sponge, following 100 cycles of rinsing and wringing with water, to provide a 100% reduction of microorganisms in the cellulose sponge within 5 minutes. 
     
     
       7. The method of  claim 1 , wherein the biguanide has the formula: 
       
         
           
           
               
               
           
         
       
       wherein:
 X 1  and X 2  are hydrogen or an aliphatic, cycloaliphatic, aromatic, substituted aliphatic, substituted aromatic, heteroaliphatic, heterocyclic, or heteroaromatic compound, or a mixture of any of these; 
 Y 1  and Y 2  are an aliphatic, cycloaliphatic, aromatic, substituted aliphatic, substituted aromatic, heteroaliphatic, heterocyclic, or heteroaromatic compound, or a mixture of any of these; 
 M is a number equal to or greater than 1; and 
 Z 1  and Z 2  are hydrogen. 
 
     
     
       8. A method of making an antimicrobial cleaning article, the method consisting of:
 providing an anionically functionalized cellulose sponge, wherein the anionic functional groups are formed during the manufacture of the cellulose sponge; 
 absorbing into the cellulose sponge an input solution consisting essentially of water and biguanide having cationic functional groups; 
 bonding the cationic functional groups of the biguanide to the anionic functional groups of the cellulose sponge; and 
 packaging the cellulose sponge with biguanide bonded thereto in a sealed package; 
 wherein the packaged cellulose sponge optionally includes a material selected from the group consisting of a dye, a perfume, a fragrance, a surfactant, and reinforcing fibers; and 
 wherein the packaged cellulose sponge does not include humectant. 
 
     
     
       9. The method of  claim 8 , wherein the biguanide has the formula: 
       
         
           
           
               
               
           
         
       
       wherein:
 X 1  and X 2  are hydrogen or an aliphatic, cycloaliphatic, aromatic, substituted aliphatic, substituted aromatic, heteroaliphatic, heterocyclic, or heteroaromatic compound, or a mixture of any of these; 
 Y 1  and Y 2  are an aliphatic, cycloaliphatic, aromatic, substituted aliphatic, substituted aromatic, heteroaliphatic, heterocyclic, or heteroaromatic compound, or a mixture of any of these; 
 M is a number equal to or greater than 1; and 
 Z 1  and Z 2  are hydrogen. 
 
     
     
       10. A packaged antimicrobial cleaning article made by the method of  claim 8 . 
     
     
       11. A packaged antimicrobial cleaning article made by the method of  claim 9 . 
     
     
       12. An antimicrobial sponge consisting essentially of a cellulose sponge, water, and biguanide bonded to the cellulose sponge through the interaction of cationic functional groups on the biguanide and anionic functional groups on the cellulose sponge; wherein the cellulose sponge maintains at least 0.02 weight percent bonded biguanide, based on a dry weight of the cellulose sponge, following 100 cycles of rinsing and wringing with water to provide at least a three log reduction in microorganisms in the cellulose sponge; wherein the cellulose sponge optionally includes a material selected from the group consisting of a dye, a perfume, a fragrance, a surfactant, and reinforcing fibers; and wherein the cellulose sponge does not include humectant. 
     
     
       13. The antimicrobial sponge of  claim 12 , wherein the biguanide has the formula: 
       
         
           
           
               
               
           
         
       
       wherein:
 X 1  and X 2  are hydrogen or an aliphatic, cycloaliphatic, aromatic, substituted aliphatic, substituted aromatic, heteroaliphatic, heterocyclic, or heteroaromatic compound, or a mixture of any of these; 
 Y 1  and Y 2  are an aliphatic, cycloaliphatic, aromatic, substituted aliphatic, substituted aromatic, heteroaliphatic, heterocyclic, or heteroaromatic compound, or a mixture of any of these; 
 M is a number equal to or greater than 1; and 
 Z 1  and Z 2  are hydrogen.